Pressure-control apparatus



Jan. 6', 1931. J; A. CAMPBELL PRSSUR CGNTROL APPARATUS Filed April 19. 1927 Irma/Mor. m /4 :fifa/wey.

c universal use.`

Patented Jan. 6, `1931 yJULIAN A. CAMPBELL, or Lone BnAori, 'CALIFORNIA rRnssUnn-conrnon APPARATUS L Application" nica April' 19,

` This invention has-to do vvithfpressure control apparatus of vthe general type adaptable for use, as a typicalexample, for controlling the gas or vaporpressure ine-oil tanks Jalthough there are several different ob-V jects of the presentimprovements, most of them will be best understood. from the l ollowing` detailed description.y 1 I 'niaysay preliminarily, however,'that"the primaryr object of the present invention is to provide a pres# sure control apparatusvvhich is capable of `sfrea't sensitivityv of operation, and in which the sensitivity is Wholly. and completely adjustable.

I Ahave not only desirableto have ja pressure control that isrcapable of extreme sensitivity, but also one in VWhich sensitivity may beeasily and readily regulatedto suit varying conditions. 1Without going into details, I may mention the fact that the amount of vapor or gasivliich has to be handled by such a pressure control apparatus varies from vseason to season and alsoV varies under other 'changing conditions. For instance, tlievariation of'tei'npeiatures during summer causes oil vaporization at a ,rater much higher than the teinperature'varia-y tion in Winter;4 andv calls for an adjustment of sensitivity that Will permit the apparatus readily tohandle a large quantity oi vapor in a comparatively short time. And also, as an instance, ivhen an oil tank is being: iilled or emptied rapidly, it is desirablefthatjthe sensitivity of the device maybe temporarily adj usted to enable it eiiectively totake'` care of the large volume of vapor orffgas which must necessarily be taken out or," put into the tank'V to maintain an equable pressure. `'urtherfinere,` some tanks'arenot capable'V oiifvvithf standing the pressure variations that otherl tanks may safely stand, andso' forvveak tanks it isespecially desirable that 7the :apparatus e adjustable to great sensitivity.

One of the major' objects-ot` iny'present invention is, by'having a'full adjustment of sensitivity. 'vvitha capability of extreme seii-v sitivenesato provide an apparatus capable of How my present inventioniaecomplishes its purposes, and VarOll Qtheadvantages resid? found in my experience that it is i927. sei-inno. 184,899.

ing in theinvention, Will be best understood from theiolloiving detailed description, reference Yfor thatpurpose being had' to the'accompanying'drawings, in which:

Fig 1 is aside elevation of my improved apparatus;fand

1 FigrZ isa plan of the same. c f l illustrate the apparatusy as being mounted directly upon Athe top lOof the tank, al-

' though of course it might be mounted/in any otlierlo'cation and :suitablyv connected With the tank. Mounting the apparatus on top the tank'facilitates greatly the making of connections and puts the apparatus close to the tank @so that there is no substantial delay in its action and there is no liability ofits be-l f innV actuated by surges in pipe lines.k

The gasometer illustrated at G is typical of `any device vWhich/Will expandand convtractby virtue of variation in applied pres.-

sure. l select a-gasometer for this purpose because of its,comparativelygreat sensitivity and its freedom .from friction.v The gaslometer lWill need no specific description,

as devices'of this general type ,are Well known; itis necessary here only to` say that the ymovable, upper member 1-1 of the gasonieter-*is"pivotally connected V byl link 12`vvitli one end of a balance Alever L which is centrallypivotedat12aon 'a suitable support` 13. -Support 13 may be mounted on a flanged plate 14,' which conveniently rests upon the bodies of the two valves 15 and 16,

valve V15 being the pressure outlet valvek and Valve V16 thepressure inlet valve. Both these valves are preferably of the.balaneedpressure type sothat'tliey move freely and are' not affected in their `movements by the pressures Which they. arecontrolling; A gas and vapor outlet pipe vWill ordinarily connect With valve 15 andY a. gaspressure inlet pipejvvill connect With yvalve'l,V gas being constantly rept present at inlet valve 16 under a VVsuitablepressure, usuallya pressureV sub-V stantiallyhigher than that desired tor be maintained in the tank, andthereforevvalve 16 Ymay beV comparatively small.V Valve 16 has a communicating pipe 18 which connects with the standpipe 19 that communicates with I valve ,lated also communicates with the inf lil@ ' selves.

teriorof the tank, standpipe 19 serving convenient-ly as the supporting member 'for the valves and their actuating apparatus. vThe lower member or tanlr20 ofthe gasometer may conveniently be mounted upon angle iron members 21 which are secured to standpipe 19, the gasometer: end of the apparatus being supported by astandpipe 22 whichv also communicates with the interior of the tank and, at its Aupper. end, with the interior of the gasometer. Angle iron lmembers 21 serwto tix' the gasometer in proper position with relation to the valve parts of the apparatus.

At the end of the balance-lever L opposite the gasometer a suitable weight WV may be hung, this weight. being conveniently inthe form.r of a container into which a measured or ascertained weight of any suitable substance may be placed, preferably a substance th'atdoesy not. vary in weight by Vexposure to atmosphere or to theweather. The amount of weight at WV maythus be easily and conveni ently varied to'suit circumstances. The leverage system made up of the gasometer head 11, lever- VL and weight W', may of course be adjusted to be in normalequilibrium position (in this case a substantially horizontal position of lever L) either when the pressure under the gasometer head is equal to atmospheric pressure, or more'or less than atmospheric pressure. F or instance, if the lever arms are equal and the weight atW is equal to the weight of the gasometer head, thenthe lever system is in equilibrium when the pressure f underthe gasometer head equals the atmos# p'heric "pressure atf that instant. Suitable variation of'weight at W willmake the system' come to its normal position when the pressure under the gasometer 'head is eithergreater or less than the Vatmospheric pres# sure rand thus,'as will be seen', the apparatus canbe generally adjustedto-lreep any desired pressure, relativeV to atmosphere, inthe tank. Thepressurein the tank is at all times maintained'in a certain relation tothe instant at-.

' mosplieric pressu`re,as.`will be readily understood from the consideration of the natureV of actionl of the gasometer.

In th'evpresent improved apparatus the entire weightof the lever system that includesk the gasometer headyand weight WV is supported'by the support -13and is not at' anytime imposed` upon` the valves them?.- Myfpresent system enables .mef toV imposeV upon the valve'sfthemselves, to close them, suitable forces determined solely'with reference to the forces necessary Vto elosethe valves;A not being determined or affectedin the least` by the weight ofthe gasometer- .-Ihead and of weight WV. "Each valvehas aj stem 25 or'26 fand thel upper end of each stem is 'connected with 'a valve lever 27 or- 2K8V at a point-intermediatethe ends Vof the valve lever.Y One end of each valve lever? its pivotedat. V29' tothe upper 'end ofl aflinlrSOVV holes 31a', so that the links 30 may beshifted in position ,to'shift the pivot points 29 of the two valve levers toward or from the two valve. stems, such adjustment being one means of adjustably varying the sensitivity ofthe apparatus. And it will be noted that these 'adjustments with relation to each valve lever may be made independently, so that the sensitivity of either valve actuation may, be. adjusted independently of the` Vsensitivity of the other. In Fig. 1 for in stance I showthe effective `pivot point 29 of outlet valve-lever 27varranged closer to the valve stem than is the case for valve lever 28 of the inlet valve. Each of these levers is provided with a suitable weight 32 sutilcient to movey the levers ldown and close the valves, the levers being raised by stirrups 33 which dependA from balance lever L,;these stirrups beingadjustable along balance lever L to dierent positions. VThe stirrups only lift the valve levers, they,v cannot push .the valve levers down. With the `pivot point of a valve lever directly under .pivot point 12a of the balance lever (as is shown to be the caseV for valve lever 28 in Fig. 1). it will readily be seen that the position of stirrup i 33 has nothing to do withvariation of the sensitivity of actuation of the `inlet valve 16. However, if the lpivot point of the kvalve lever is etectuallyV shifted toward the valve stem, ars-is illustrated'to be the case with valve lever 27then the relative position ot' stirrup 33'is a factor in the variation and regulation of valve `actuation sensitivity. It will be remarked, ofcourse, that the amount of Weight at 32, and the position or these weights on thev valve levers, are also factors in the Svalve actuation sensitivity, and may .be used as such; but in practice l prefer` to use liXed weightsat32, determining those weightsl and their positions as being substantially suiicient always to close ,the respective'valves, and Ythen .to obtain VAavoiding liabilityfofl `a valve sticking due to kbeing closed V under-,too great a force.

. To illustrate Ythe Vpossibilities of sensitivity Lvariation/'I shall refer first Ato the outlet valveV arrangement as shown. W'ith the,` stirrup "33 in ,the position Aillustrated it Awill be Y seen: that "balance leverrL, onrmoving upwardly at its lett hand end, as 1t doesV when Vvthe pressurein the gasometerfrises, may be said to be under aleverage disadvantagen'of about' l'to 2 1 with relation to lever '27,' the pointl ofcony nection ofthe stirrup to lever L'being about twice as far from lpivot;point"121jasjis=the point of connectiony of that' stirrup with lever 27 from its pivotal point 29." Moving that stirrup 33 tothe right vvill furtherincrease the leverage disadvantage*` of levertL,

or in other Words Willincrease the; advantage of lever 27 over` lever L; While moving the stirrup 33 vto the left Will correspondingly decreasetheadvantage which lever 27 has *overy leverL. rThus as the stirrup 33 is movedl toward the leftk thesensiti-vity of opening actuation of valve 15 is increased;A that is,"`1t requires a smaller increase in.

gasometer pressure rto open valve 15. VThe limit of sensitivity Would be reached in this arrangement when the stirrup is inits position furthest tothe left andiflever 27 Were made long enough, as it might readily be, and stirrup 33 placed directly over thev gasometer, the relative advantageof lever 27 overbalance lever L vvillbe seen to ap-v proach unity, and `in that casethe valve 15 Would be lifted When the pressureincreaseV under the gasometer head became a little greater than the Weight 32.

If it be desired "n'adjustments vto give rneither of the Ylevers an advantage over the` other, then the pivotpoint of' theV valve lever may be yarranged as is shown for theinlet valve lever 28 of Fig. 1, directly under` the pivot point 12 of lever L. VVitlrthat arrangement the sensitivityfof opening moves ment of the valve is increased, because in no position'of stirrup 33 does lever. 28 haveany advantage over leverL, with the result that (applying the observation noW tolever28V and the pressure inlet valve) Athe pressure inlet'v'alve 'will be openedfjust asv soony as the decrease of total pressure vunder the:V

vgasometer lhead becomes equal lto alittle Yto ` more than the Weight at 32. In speakingfof increases or :decreases of pressure, I mean increases and vdecreases with relationto the normal'pressure for which Weight 1W is set. Thus the sensitivity ofthevalve actuation may be adj ustably varied by tWo adjustments,

in addition to the adjustment Vof Weights. 32.V

ln the first place the sensitivitymay. be ladj usted by varying the position of thestirrup` f 33, provided the links 3() yare not directly un-j der pivot point 12; and secondly may be. ad#

. justed by Aadjusting the links -and thepivotY points29 toward or avvayfrom a position rdirectly Aunder pivotr point 12. Generally speaking an adjustment of pivot points29 to- `Ward the central position under pivot 12, the

position'of'the stirrups beingiXed, will increase the sensitivity of valve actuation, and an. opposite adjustment of the pivot point' 29 will decrease the sensitivity of valve actuation; Andes Iliave before explained, an ad-J f justment ofthe stirr'ups awayfrom the `centralpivot'point l12 willyif the corresponding pivot point 29 yis not directly under pivot` p`ointv12, also increase the sensitivity of valve actuation; While an lopposite adjustment' `of the stirrups will decrease that sensitivity.

Within theinherent physical limits of the.k apparatus thesensitivity of both valves mayy be adjusted as desired. Of course .the greatest sensitivity of valve actuation is limited by certain iXed relations in anygiven apparatus.

That" greatest sensitivity is fundamentally f' determined by the size (pressure area) lof the gasometerand by the-Weight necessary to close -thevalves` But I 'find that, Without having toiprovide Yan excessively large vgasom'-` eter', and Vstill 'using a Weight that Will invariably close thevalves, the maximum sensitivityofthe apparatus is suliicient for all requirements. The structure and designof the.-

apparatusare such that the gasometer may be made comparatively large and lthat afcomparatively heavy Weight may be used at WV Without putting anyof that dead Weight uponl the valves themselves.v And' another point Which I mayk mention is this: that if in any` icasetheweights at (32 should not be sulicient tofmove'a valve c1osed,'forfinstance if the down on'the Weight, will knock Vthe-,Weight andlits valve lever down.'

` From a maximum sensitivity it Will readily valve becomes stuck, the lever lL, coming Y be seen .that adjustments may be made through'a range 'up lto veryy coarse sensitivity,

so that, if it is' desired, the range of vtank A pressureLbetvveen the pressure that opens the outletvalveand that .that'opens the' inlet valve lmay be adjusted'j` to be' comparatively large. Furthermore, it will be noted thatthe sensitivity of either valve actuation maybe adj ustedin complete independence of the adjustment of the other, and furthermore that the adjustment ofthe `main leverage system `to determine thenormal pressure held in the tank, is also completely independent of the sensitivity adjustments.`y Thus the main s leverage system may be adjusted, byl adjustatmosphericpressura the main leveragesys tem Willj then be` in'equilibrium iwith both valves closed, the parts being in the relative positions shown in Fig. 1. Now suppose that it is desired to makel the valve control extremely sensitive as to keepingl the pressure upgto the selected pressure of two ounces per square'inch, but that it is not desired to let vapor pressure olf from the tank until the va-VY 'por pressure v,reaches a point considerably u above two ounces, 1n order-to save vapor.

ThusV for instance let us suppose that it isl desired to-be certain that the tank pressure Will-:never under a-ny circumstances fallfbelow onevounce'per squarein'ch (to avoid anj7 possibility ofra vacuum ever developing in a tank), but that vapors Will` not be taken olf from tlietank until the pressure `reaches ounces per square inch. Without' going into detail as to adjustments it Will'be readily understood from what I have said that the sensitivityof the pressure inlet valve actuation may be adjusted so that, upon-adecrease of one -ounceper square inch inpressurein vthe gasometer, the inlet valve Will be lifted, feed-2 ing pressure into the tank.- And likewise it Will bereadily understood'hovv the leverage system for-the' outletvalve may be adjusted sothat =the outlet valve will not be lifted and openedl until-the tankpressure has increased bythree ounces` per square inch. l

If forany'reason it is desired either item*-V porarily or permanently to change/adjustments, such changes are very easily and quickly made.

porarily to increase the sensitivity' of the outlet yvalve to Itake care `of large quantities ofk For instance if it is desired temvapor-While the tank is being iilled, such ad just-mentcany be made quickly, and the adjustment as quicklychanged back to normal after the illing operation is completed. Like- V`Wlise sensitivity ofthe inlet valve may be that the tank pressure-may be kept up durtemporarilyf-adjusted to-a very fine pointso ing a period Whenthe tank is Ybeing quickly emptied. Other,v instances `under which 'a temporary or more orflesspermanent` changeY in `adjustment may be desirable are vvell' known to those skilled in the art and need not be -detailedhere by me. if s' Iclaim:v v

l. A- pressure control apparatus, f embodying an element movable'by virtuelof variations in applied pressure, a pressure relief valve, a pressure inlet valve, a pivoted' leverV actuated by said.` element, adjustable Vvveight means connected lto the lever andadjustably 'w21' A pressure control apparatus, embodying an.r element movable; byv virtue` of variationsin applied pressure, `a pressure relief valve, a pivoted lever actuated by saidelement, adjustable vWeight, means connected to the-'leverl and adj ustably balancing it against said felement, a :valve actuating VleverY connectedwith each valvasaid valve-levers eX- tending lsubstantially parallel with saidpivoted lever and arranged on oppositesides of its .pivot point, each valve lever having a ul'crum adjustable along its length, means tendingl with constant torce, to move said levers'to close the valves, and'connections between the element actuated leverand the valve levers, adjustable `along their length, and adapted to move tlievalve leversto open the valves. o u

'3. A pressure control apparatus, embodying an element movable by virtue of variations nin appliedupressure, a pressure relief valve,` a pressure inlet valve, a pivotedlever `actuated by said element,Weight means connected to the lever and balancing it against said element to balance it normally in substantially liorizontal'position, a lever connected With each valve and havingL a ulcrum adjustable along its length to andfrom a position in vertical alinement With the pivot point of saidpivoted lever, a Weight on each of said valve levers tending to depress the levers and closethe connected valves, and a connection between the element actuated lever and each of tlie valve levers adaptedto raise the valve levers and open thevalves.

4; A pressure control apparatus, embodying an element movable by virtue of variations in'applied pressure, a pressure relief valve, a pressure inlet valve, a pivoted lever actuated by saidelement, adjustable Vmeans connectedt-o the lever for adjustably balancing it against said element, a ulcrumed lever connectedwitheacli valve, aweight on each tocl'ose theconnected valves, and connections betWeent-he element actuated lever and each valve lever adapted to raise the valve levers andV open the. valves, said connections being adjustable .in position along the lengths of the levers to vary the effective lever arms.

5; AV pressure control apparatus, embodying an element movable by virtue of variations in applied, pressure, a pressure relief valve,l a pressure inlet valve, aqpivoted lever actuated by said element, means conn'ectedto the leverforbalancing it against said element tobalance it normally in substantially horizontal: positioma pair of substantiallyhorizent-all valve levers vbelow the elementactuated leverfreach connected: to onev valve and valve lever tending todepress .the levers and Weighted to move .the valves'down, and means adjustable Aalong the length of the element' actuated lever depending tliereiiromand adapted toe'ngage 'the valve levers toraise themandtheir connected valves. Y 1

pressure inlet valve, a pivoted lever actuated by said element, adjustable Weight means con- 6. .A pressure control apparatus, embodying an element movable by virtue of variations inapplied pressure, a'pressurereliefvvalve, a

'March, 1927.

of substantially horizontal valve levers below the element actuated lever, each connected to one valve and Weighted to move the valves down, each lever having a fulcrum adjustable 1 in position to and from its valve Connection and stirrups adjustable along the length of v the element actuated lever depending therefrom and extending under the valve levers to raise them and their connected valves.

In Witness that I claim the foregoing I have hereunto subscribed my name this 29th day of JULIAN A. CAMPBELL; 

